Plot summary
The Enterprise is en route to a briefing concerning a situation in Cardassian-Federation demilitarized zone. Meanwhile, newly promoted Lieutenant Ro Laren attends a welcome back party after graduating tactical training on Earth.
The Enterprise responds to a distress call from a Cardassian warship under Maquis attack and quickly forces the Maquis to withdraw. The Enterprise later rendezvous with Vice Admiral Nechayev's ship, she informs Picard of a Starfleet plan to infiltrate the terrorist cell using Ro Laren.
Ro finds her way to a bar where she is contacted by members of a Maquis cell, and after verifying her cover story, they quickly accept her into their ranks. She forms a bond with Macias, whom Ro obviously sees as a father figure. The Maquis know of a Cardassian biogenic weapon project and plan a preemptive strike; however, Macias points out they are short of critical medical supplies. Ro offers to steal the needed supplies from the Enterprise, which she manages with some covert help from the crew.
After debriefing Ro on the Enterprise, Captain Picard plots to use a ruse to draw out the Maquis and then cripple them with a Federation fleet hidden in a nearby nebula. Although Ro is troubled by his plan, she returns to the planet and convinces the Maquis leadership to plan an attack on a Cardassian convoy supposedly carrying components for the biogenic weapon. Cardassian militia raid the compound in a surprise attack, killing Macias. As he dies, he tells Ro that other Maquis like her will step forward to carry on the fight in his place.
Shortly thereafter, a very unsettled Ro meets with Picard because she is having second thoughts. Picard decides to send Commander William Riker with her to keep an eye on her and assure the mission proceeds as planned.
The day for the raid arrives, and as the Maquis fighters close in, Ro decides she cannot go through with the mission. She exposes the Federation attack force, and the Maquis ships break off their attack. With great regret, Ro asks Riker to apologize to Picard on her behalf before beaming to a Maquis vessel. On the Enterprise, Riker tells Picard that Ro seemed very sure of her decision; her only regret was in letting Picard down. The episode ends on Picard's expressionless face as he contemplates Ro's betrayal.
Credits
Adapted from Wikipedia contributors, Preemptive Strike (Star Trek: The Next Generation). Paragraphs and formatting adjusted; illustrations, reference markers, block quotations and non-story material omitted.